Affinity Labelling of Yeast Phenylalanyl‐tRNA Synthetase with a 37′‐Oxidised tRNAPhe

Abstract
Yeast phenylalanyl-tRNA synthetase was specifically labeled with a 3''-oxidized tRNAPhe. Stoichiometric inactivation was achieved with the incorporation of 2 mol oxidized tRNAPhe/mol enzyme which corresponds exactly to the stoichiometry of tRNA binding. The labeled peptide was isolated using a quick chromatographic procedure which can be applied to any covalent complex formed between a tRNA and an aminoacyl-tRNA synthetase. The isolated peptide (18 amino acids) encompassed the unique cysteine sequence of the smaller .beta. subunit of the enzyme.